Cannot infer type argument from overloaded function with explicit self types #14943

from typing import IO, Generic, AnyStr, overload

from _typeshed import SupportsRead, SupportsWrite

class C(Generic[AnyStr]):
    @overload
    def write(self: C[str], s: str) -> int: ...
    @overload
    def write(self: C[bytes], s: bytes) -> int: ...
    def write(self, x):
        return 0

def cp(src: SupportsRead[AnyStr], dst: SupportsWrite[AnyStr]) -> None: ...

def g(a: IO[bytes], b: C[bytes]) -> None:
    # error: Cannot infer type argument 1 of "cp"
    cp(a, b)

import tempfile
import shutil
from typing import IO

def f(model_fileobj: IO[bytes]) -> None:
    with tempfile.NamedTemporaryFile() as tmp_file:
        # error: Cannot infer type argument 1 of "copyfileobj"
        shutil.copyfileobj(model_fileobj, tmp_file)